Thursday, October 21, 2010

Action on Smoking and Health Reinforces Its Claim that 30 Minutes of Smoke Exposure Raises a Nonsmokers' Fatal Heart Attack Risk to That of a Smoker

This is a tale of two organizations. When it was pointed out to Americans for Nonsmokers' Rights (ANR) that its web site contained a hysterical claim about the dangers of smokers' clothing that was based solely on a press release from a textile institute, ANR promptly removed the material from its web site. In contrast, when it was pointed out to Action on Smoking and Health (ASH) that its even more hysterical claim was false, ASH didn't remove the claim. Instead, it reiterated, reinforced, and strengthened the claim.

Today, ASH is claiming that: "even 30 minutes of exposure to small amounts of drifting secondhand tobacco smoke can increase a nonsmokers' risk of a heart attack to that of a smoker, and can trigger a (sometimes fatal) heart attack."

It has moved this claim from one of many claims made on a web page to a page of its own, giving it special prominence.

The Rest of the Story

To see how obviously false this claim is, simply reverse it. What ASH is stating is that a smoker's risk of a fatal heart attack is no higher than if he never smoked in his life but merely was exposed to secondhand smoke for 30 minutes.

Obviously, that is false.

In fact, I would say that the claim is severely damaging, because it truly undermines the public's appreciation of the very real and severe cardiovascular hazards of smoking. If the public believes what ASH is saying, then they will believe that active smoking puts them at no higher a level of risk for a fatal heart attack than breathing drifting tobacco smoke for 30 minutes. Such a belief could have tragic consequences, as it would undermine public health messages that we have been sending out for the past five decades.

ASH's claim also undermines the importance of the dose-response relationship between cigarette smoke exposure and heart attack risk. If it is true that a smoker's risk of a heart attack is no higher than someone who walks into a smoky rib shack for 30 minutes one time, then smoking for 40 years doesn't put you at any increased heart attack risk as smoking for 20 years, or for 1 year for that matter. Smoking 4 packs a day isn't any worse than smoking a few cigarettes a day. And most devastatingly, quitting smoking apparently will not reduce your heart attack risk at all if you still hang out with your smoking friends for a half hour on occasion. So why quit smoking?

ASH's claim is based on a number of studies, especially one by Otsuka et al., which found that 30 minutes of secondhand smoke exposure produces endothelial dysfunction in nonsmokers, and reduces their coronary flow velocity reserve to the same level as that in smokers. However, there is a critical difference between the finding of reduced coronary flow velocity reserve and the finding of an increased heart attack risk. In fact, having reduced coronary flow velocity reserve does not equate to being at an increased risk of a heart attack. In the healthy volunteers who were studied by Otsuka et al., there was no increased heart attack risk faced by these patients. Had there been such a risk, then the study would have been unethical and it never would have been approved by an institutional review board. Certainly, the subjects would have had to be warned that they would face an increased risk of heart attack and possibly death.

Moreover, eating a hamburger reduces coronary flow velocity reserve to roughly the same extent as in an active smoker. Would it therefore be accurate for ASH to claim that "eating a single hamburger can increase a person's risk of a heart attack to that of a smoker?" Of course not. If you walk into McDonald's and order a hamburger, you may be at risk of disease, but not from immediately keeling over from a heart attack.

Luckily, the tobacco companies are a little more honest than ASH is being here, and they have not taken this opportunity to claim publicly that: "Smoking puts you at no more risk of a heart attack than eating a single hamburger." Based on ASH's statement, the tobacco companies could accurately make such a claim. The tobacco companies aren't misrepresenting the science about this. Why is ASH?

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About Me

Dr. Siegel is a Professor in the Department of Community Health Sciences, Boston University School of Public Health. He has 32 years of experience in the field of tobacco control. He previously spent two years working at the Office on Smoking and Health at CDC, where he conducted research on secondhand smoke and cigarette advertising. He has published nearly 70 papers related to tobacco. He testified in the landmark Engle lawsuit against the tobacco companies, which resulted in an unprecedented $145 billion verdict against the industry. He teaches social and behavioral sciences, mass communication and public health, and public health advocacy in the Masters of Public Health program.